The invention relates to a system comprising an internal combustion engine and a fuel cell, which particularly serves to provide the locomotion of a vehicle, and comprising a fuel cell, which serves, among other things, to generate current for electrical units of the vehicle.
Vehicles that are equipped with both an internal combustion engine and a fuel cell, in which the internal combustion engine serves to provide locomotion for the vehicle, and the fuel cell serves, among other things, to generate current for electrical units of the vehicle, are already known in the state of art.
Until now internal combustion engines and fuel cells have been installed separately from one another. In this manner it is thought, that, because of current space limitations in the installation area, a conventional starter battery should be installed.
However, especially after a vehicle has been switched off, the internal combustion engine and the fuel cell cool down in parallel, allowing the heat that is stored in these units to escape into the atmosphere. Although the fuel cell is usually held within an insulated housing, this only serves to delay the total loss of heat. In today's high-temperature fuel cells, the operating temperature is around 850° C. Following a cooling-off period of 1, 2, 4, or 7 hours, the temperature of current state-of-the-art fuel cells decreases to 750° C., 650° C., 600° C., or 400° C., respectively. Due to this cooling effect, the system-optimizing potential that would result from combining the heat from the internal combustion engine and the fuel cell cannot be fully utilized. The internal combustion engine cools off relatively rapidly, so that when the engine is restarted, the emission disadvantages of a cold start must also be taken into account.
An aspect of the present invention is thus to provide a system that comprises an internal combustion engine and a fuel cell, in which the above-named disadvantages are avoided to the greatest possible extent.
This aspect may be attained in that the fuel cell is thermally coupled to the internal combustion engine. In particular, the design involves a thermal coupling of the internal combustion engine, in other words the internal combustion engine of the vehicle, and the fuel cell. In accordance with one design, the thermal coupling is achieved in that the fuel cell is positioned on the engine block of the internal combustion engine, or is at least partially integrated into the engine block.
With a design in which the thermal insulation on the primary drive side is less prominent than the thermal insulation on the other sides of the fuel cell block, a thermal exchange is promoted in this location. This effect can be intensified via measures designed to improve heat conductivity between an insulation box and the engine block.
Alternatively, the heat from the fuel cell can be temporarily stored in a heat accumulator, and supplied to the internal combustion engine as needed.
In accordance with a further alternative, it is possible for the thermal coupling to be implemented via a fluid circuit, via which the heat from the fuel cell system is transferred to the internal combustion engine. The cooling circuit for the internal combustion engine is especially well suited for this purpose, and, in accordance with a special design, can be driven by the fuel cell.
Overall, with the measures described above, heat exchange effects between the fuel cell and the internal combustion engine can result, whereby the energy consumed by the vehicle when it is restarted, and the emission data, are improved by utilizing the lost heat from the fuel cell. Furthermore, it is possible to activate the fuel cell independent of primary engine operation, for example for engine-independent air conditioning or heating, or when the vehicle is stationary. In this case, the lost heat given off by the fuel cell contributes to heating the internal combustion engine. Overall, then, the internal combustion engine remains at a temperature level that, for example, eliminates the necessity of cold-start enrichment, along with the associated disadvantages related to fuel consumption.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.